OSX 10.11.1 El Capitan, Changing the Default Mail Client

I wanted to quickly share a tweet from Tweetbot to a friend by email, I was surprised when “Apple Mail” launched and asked me to setup an email account, I do not use “Apple Mail” I was using Airmail as my primary email client at the time.

What should have been a quick change of settings turned into a 10 minute battle with El Capitan to change the default mail client!